I am going to the smoky Mts first of march and need help on a good layering system. Cheap
My experience in the smoky's in march are that the lows are generally in the 30s, highs in the 50s... but I remember one trip where it dropped a bunch of snow on use and got to do something like 20F at night. We also had one trip were it got up into the 70s. The one consistant in my experience was rain. I don't think I have ever had a dry day in the smokies. I have heard it happens, and I have seen pictures of clear days, but in the 100+ days I have camped and backpacked in the smokies I have been rained on.
As to cheap layering... the cheapest that would work for me would be a light weight long sleeve coolmax base $10, a 200wt fleece (you most likely already have one, otherwise $20 at target, etc), frogg toggs rain suit ($85, call them for less $$ closeout deals) or if you are really gentle and not bushwacking rainshield o2 rain suit ($45), convertable nylon trekking pants ($30 someplace like sierra trading post), and a warm hat. I would bring a light weight base for my legs in case it got surprising cold.
If it was me, I would take a high loft synthetic jacket or vest like the MEC Northernlite Pullover of the Montbell Thermawrap rather than a 200wt fleece because they are lighter, more compact, and warmer than the fleece.
More thoughts / options on http://www.verber.com/mark/outdoors/gear/clothing.html